Aim: Plasminogen activator inhibitor 1 (PAI1) plays a key role in the regulation of extracellular matrix (ECM) degradation. ThePAI1 gene is therefore an excellent candidate gene for diabetic nephropathy. The aim of this study was to employ gene resequencing to identify common DNA polymorphisms in thePAI1gene, and subsequently assess haplotype tagged single nucleotide polymorphisms(htSNPs) using a case control design. METHODS All nine exons, exon-intron boundaries, introns 1, 4 and 7 and approximately 3 kb upstream and 5 kb downstream of thePAI1 gene were screened for DNA polymorphisms in 15 case and 15 control subjects using WAVE denaturing high-performance liquid chromatography technology and confirmed by DNA sequencing. Polymorphisms were genotyped in 86 healthy individuals using direct sequencing and haplotype tagged single nucleotide polymorphisms (htSNPs) identified. Genotyping of the htSNPs was performed in 583 Type 1 diabetic patients (222 with nephropathy, 361 without nephropathy)using Pyrosequencing.
Results: Twenty-one polymorphisms with a minor allele frequency (MAF)>1%were identified; 14 had a MAF> or =10%. Five htSNPs [c.-1968_69insG, c.43 G-->A (Ala15Thr), c.1092-105 A-->G, c.*1737 G-->A, c.*3711 C-->T] were identified. Haplotype frequencies were similar in case and control groups (likelihood ratio chi2 test,P=0.66).
Conclusion: It is unlikely that common polymorphisms of thePAI1 gene strongly influence susceptibility to diabetic nephropathy in the White Type 1 diabetic population.